Tag: process control
-
Basic Features of Modern PID Controllers
Most modern PID controllers have the following features: Manual versus automatic modeOutput trackingSetpoint trackingAlarm capabilitiesProcess variable (PV) characterization and dampingSetpoint limitsOutput limitsPID tuning security Manual and Automatic Modes When the controller manually calculates … Read more
-
Direct Digital Control (DDC)
In direct digital control (DDC) a single computer is able to carry out PID control for multiple loops at the same time make that loop data accessible between loops for purposes of cascade control, feedforward control, ratio control… Read more
-
P&IDs and Loop Diagrams
Process and Instrument Diagrams (P&IDs), also called Piping and Instrumentation Diagrams and Loop diagrams are construction and documentation drawings that show the flow of the process and illustrate the instrumentation control and measurement instructions, wiring and connections to the process.… Read more
-
Ratio Control
In some processes, it is a common requirement for two flows to be kept in precise ratio to each other for example, a gas or oil and air in combustion control, and reagents being fed to a chemical reactor hence … Read more
-
Feedforward Control
Feedforward control is based on principle of pre-emptive load counter-action i.e. if all major loads (i.e. disturbances) on a process variable are monitored, and their effects on that process variable are well-understood, a control system programmed to take the appropriate … Read more
-
Benefits of Cascade Control
We know very well that closed loop control provides increased performance over open loop control. So it would be rational to expect benefits from adding inner control loop around plant items that have degrading overall performance. The Figure (a) below … Read more
-
The Basics of Ladder Diagrams for Programming PLCs
The ladder diagrams are universally used as a symbolic and schematic way to represent the interconnection between the elements in a Programmable Logic Controller (PLC). The ladder network is also used as a tool for programming the operation of PLC. … Read more
-
What is Sequential Control System?
This is a control system that manages a process defined by a series of tasks to be performed i.e. a sequence of operations, one after the other. Each operation in the sequence is performed either for a certain period of … Read more
-
Basic Features of Distributed Control Systems (DCS)
In distributed control system, each process has its own separate controller located at the site. These local controllers are interconnected via a local area network so that all controllers on the network can be monitored or reprogrammed from a single … Read more
-
What is Process Control?
Process control can be defined as a control system that manages a particular industrial process so that a uniform, correct output is maintained. It does this by monitoring and adjusting the control parameters such as the flow rate or temperature … Read more